In clinical trials, the most common adverse reactions reported were neutropenia, hiccups, decreased appetite and dizziness.
Shares of Tesaro, Inc. fell about 4.4 percent in after-hours trading on Friday after the company announced it updated its prescribing information for anti-nausea drug Varubi due to serious adverse reactions.
Varubi, a substance P/neurokinin (NK-1) receptor antagonist, was approved by the U.S. Food and Drug Administration with an IV formulation in October 2017. The drug was approved for the prevention of delayed nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy. Varubi is a moderate inhibitor of CYP2D6 and significantly increases the plasma concentrations of CYP2D6 substrates for at least 28 days. An oral form of Varubi was first approved by the FDA in 2015. In January of 2017, the FDA denied Tesaro’s injectable version of Varubi, rolapitant IV over manufacturing concerns, but the company was able to address those and scored approval in October.
But since the drug was launched in November, Tesaro noted there have been multiple reports of anaphylaxis, anaphylactic shock and “other serious hypersensitivity reactions” in the post-marketing setting. Some of the patients required hospitalization, the company said. The reactions occurred during or soon after the infusion of Varubi, with most reactions having occurred within the first few minutes of administration, the company said. Since the drug was launched in November, Tesaro said about 7,000 doses of Varubi have been administered to patients receiving emetogenic chemotherapy in the United States.
In clinical trials, the most common adverse reactions reported were neutropenia, hiccups, decreased appetite and dizziness. Additionally, the company noted that intravenous administration of Varubi was associated with infusion-related symptoms, which includes sensation of warmth, abdominal pain, dizziness, and paresthesia.
In its announcement Friday, Tesaro said changes to the labeling include modifications to the contradictions, warning and precautions and adverse reactions sections. The IV formulation of Varubi was expected to become a rival of Merck‘s Emend, which snagged about $550 million in revenue last year.
As part of a commitment to ensuring patient safety, Tesaro said it has issued a Dear Healthcare Professional (DHCP) letter which includes full prescribing information. The company said it is also taking proactive measures to have its “field force” reach out to healthcare professionals regarding the new safety information.
Healthcare providers and patients are encouraged to report adverse events in patients taking Varubi injectable emulsion to Tesaro at 1-844-4-TESARO (1-844-483-7276). The company’s medical information department may be reached at 1-844-4-TESARO (1-844-483-7276).
While Tesaro prepares to deal with the fallout from the new warning label, some analysts predict the company is still ripe as a takeover target. In addition to Varubi, Tesaro also markets PARP inhibitor Zejula (niraparib). Niraparib (Zejula in the U.S.) is the first and only PARP inhibitor that has received approval in the United States for the maintenance treatment of women with recurrent ovarian cancer, regardless of BRCA mutation or biomarker status.
